Carriage retarding mechanism for typewriters or like machines



H. L. LAMBERT El AL 2,808,144

CARRIAGE RETARDING MECHANISM FOR TYPEWRITERS OR LIKE MACHINES Filed March 4, 1955 INVENTORS HARRY L. LAMBf/W' CARL 13 s am: BY WP 7" V10 ATTORNEYS United States Patent ind:

CARRIAGE RETARDING l\ IECHANISM FOR TYPEWRITERS OR LIKE MACHINES Harry L. Lambert, West Hartford, and Carl B. Spong,

Newington, Conn, assignors to Royal McBee Corporation, New York, N. Y., a corporation of New York Application March 4, 1955, Serial No. 492,220

19 Claims. (Cl. 197-183) This invention relates to carriage retarding mechanism for typewriter or like machines, and more particularly to mechanism for snubbing or retarding the machine carriage when it is approaching a limit position in either its letter spacing or its return travel.

There have been numerous prior proposals to provide such retarding mechanisms. One of the difficulties encountered when using some of the prior retarding mechanisms is that, because of their having been constructed so as effectively to retard a rapidly moving carriage, their inherent retarding characteristics were so great as to resist movement of a relatively slowly travelling carriage suificiently to prevent its being moved completely to the desired predetermined limit position. Such a shock absorber mechanism capable of effectively retarding a typewriter carriage as it approaches the end of a long tabulating run, and when therefore moving at a relatively high speed, may have such a marked decelerating effect on a carriage moving at a relatively low speed as it approaches the end of a short tabulating run as to prevent the carriage from completing its tabulating travel before the carriage is restored to the control of the escapement mechanism. Consequently, when the carriage is put under the control of the escapement mechanism it may be one or more letter spaces away from the proper tabulation position. So too, such shock absorber mechanisms used for retarding carriages as they approach the end of return movements, i. e. movements opposite to letter spacing or tabulating movements, may interfere with proper positioning of the carriages at the end of their movements when the carriage return speed varies in consequence of the return travel being long or short. Such interference may prevent proper positioning of a carriage in its line starting position, resulting in undesirable indenting at the margin.

An object of the present invention is to provide improved typewriter or like machine carriage retarding mechanism characterized by the ability to exercise a control over the deceleration of the carriage which varies according to the speed at which the carriage is travelling when it approaches the position at which it is to be stopped. Desirably, the retarding mechanism provides greater resistance to carriage travel when the carriage is moving relatively fast at the time the mechanism is activated than when the carriage is moving relatively slowly at the time of activation.

Another object of the invention is to provide retarding mechanism having the desirable characteristic referred to and which includes a dash pot or fluid cushioning device equipped with valve means automatically responsive to differences in carriage speed for variably controlling the flow or exhaust of cushioning fluid so as automatically to provide a relatively large retarding effect when the carriage is travelling at high speed, and a relatively small retarding efiect when the carriage is travelling at low speed.

Another object of the invention is to provide mechanism of the kind referred to in which the valve means includes an element formed of resilient material capable of being deformed to greater or lesser degree upon engagement with a cooperable valve element for thereby permitting relatively restricted or relatively unrestricted exhausting of fiuid from the dash pot cylinder according to whether the relative approaching speed of the valve elements is fast or slow.

A further object of the invention is to provide typewriter or like machine carriage retarding dash pot mechanism including a valve operable initially to cause a relatively restricted exhausting of fluid from the dash pot cylinder at the instant of activation of the retarding mechanism, followed by a progressively decreasing restriction of the exhausting of fluid, irrespective of the carriage speed at the instant of activation of the retarding mechanism.

Other objects of the invention will become apparent from a reading of the following description, the appended claims, and the accompanying drawings, in which:

Figure 1 is a fragmentary view, partly in rear elevation and partly in section, showing shock absorber mechanism embodying the invention in connection with parts of a typewriter stationary frame and movable carriage;

Figure 2 is a fragmentary rear elevational view of a typewriter main frame part and portions of the shock absorber mechanism shown in Figure 1;

Figure 3 is a fragmentary perspective view of the parts shown in Figure l with part of a dash pot cylinder broken away to enable illustration of interior parts;

Figure 4 is a fragmentary perspective view of a dash pot plunger stem drawn on an enlarged scale; and

Figure 5 is a schematic view depicting shock absorber mercham'sm embodying the invention applied to a typewriter equipped with a power operated carriage returning mechanism.

For illustrating the application of a preferred embodiment of the invention to a typewriting machine, only such conventional or known parts of the machine are illustrated as are required to enable an understanding of the cooperation of the shock absorber mechanism with the associated typewriter parts. Figure 5 shows schematically a typewriter main frame or fixed rail member 1 on which a carriage rail member 2 is mounted for letter spacing and return travel. The carriage rail 2 is supported on the frame rail 1 by rollers or balls 3 in a known manner.- A carriage returning draw band 4 is connected to the carriage rail member 2 and extends to the left as viewed in Figure 5 (to the right as viewed from the front of the machine), around a guide roller 5, and thence to motor driven mechanism (not shown) for winding up the draw band 4 and moving the carriage in the return direction, that is toward the right as viewed from the front of the machine and toward the left as viewed in Figure 5, in the direction of the arrow a. The mechanism for operating the draw band 4 may be of any suitable or preferred construction, such for example as the construction shown in the patent to Hart No. 2,567,937 granted September 18, 1951.

The preferred embodiment of shock absorber mechanism shown in the drawings includes a striker unit 6 secured to a stationary frame part, for example the frame rail member 1, and a dash pot unit 7 secured to the carriage rail member 2. The units 6 and 7 are displaced from each other during most of the carriage travel on the frame, but have parts which are mutually engageable when the carriage moves into a predetermined portion or zone of travel during its return movement. However, mechanism embodying the invention may be mounted or correlated with respect to other typewriter parts in such a manner as to cause the units 6 and 7 to cooperate with each other when the carriage is traveling in the opposite direction, for example for retarding the carriage with a cushioning effect at the end of a tabulating movement or run during which the carriage travels in the letter spacing direction.

In general, the cushioning of the stopping or arresting of the carriage as it approaches a. predetermined limit of travel is eifected by the resistance to exhaustion of fluid, e. g. air, from the dash pot unit 7. The shock absorber mechanism is characterized in that it is responsive to relatively high carriage speed at the time of operation of the shock absorber mechanism for providing a relatively high degree of suubbing or shock absorbing effect, and is responsive to relatively slow travel of the carriage for providing a relatively low degree of shock absorbing or retarding effect. The dash pot unit 7, mounted on the carriage rail 2 by a bracket 3 and screws 9, comprises a cylinder having an outer wall 11, a fixed or integral end wall 12, and a piston or plunger 14 mounted for reciprocation in the cylinder 10. The plunger 14 is formed with a recessed seat 15 receiving one end of a restoring spring 16, the other end of which bears against the fixed cylinder end wall 12. The arrangement is such that normally, that is when the units 6 and 7 are not cooperable for snubbing the carriage, the spring 16 maintains the plunger 14 in about the position shown in Figures 1 and 3, that is toward the shock absorber unit 6. Integral with the plunger 14 is a stem element 17 which projects outwardly of the cylinder 10 through a central opening 18 in a removable end wall 19 held against a shoulder 20 in the cylinder wall 11 by a circular spring retainer ring 21 expanded into a groove 22 in the cylinder end wall 19. The end wall 19 is formed with a relief opening 23 for enabling air to pass relatively freely into and out of the cylinder space included between the plunger 14 and the end wall 19. An exhaust passage 24 extends axially through the stern element 17 from its outer or free end, at the left in Figure 1, to the root of the spring seat 15 in the plunger 14, and communicates constantly with the cylinder chamber between the plunger 14 and the cylinder end wall 12.

In operation, when the carriage is being moved in the return direction, that is to the left as viewed in Figures 1, 3 and 5, the outer free end of the stem 17 will engage the frame mounted unit 6 just before the carriage reaches the predetermined position at which it is to be stopped. This will cause the plunger 14 and stem 17 to be moved relatively to the cylinder 10, toward the right, as viewed in Figure l, requiring that air in the cylinder chamber at the right of the plunger 14 be exhausted through the passage 24. Since the passage 24 is of relatively small cross sectional area as compared to that of the cylinder, pressure will build up momentarily within the chamber so as to resist movement of the plunger relatively to the cylinder and thereby to retard the carriage. When the carriage has been stopped and is then moved in the opposite or letter spacing direction, causing the shock absorber units 6 and 7 'to be separated, the spring 16 will return the plunger 14 to its normal position as will be permitted by exhausting of air from the left end of the cylinder through the relief opening 23.

Novel valve mechanism incorporated in the shock absorber units 6 and 7 exercises such a control over the yielding movement of the stern element 17 as to render the shock absorber mechanism effective for exerting more or less retarding force on the carriage member according to higher or lower speed of travel of the carriage member as it approaches the position at which it is to be stopped. The construction is such that the valve parts automatically are adjusted to cooperate with one another so as to enable exhausting of air at a rate which varies inversely to variation in the carriage speed, that is to provide for relatively slow or restricted egress of air from the exhaust passage 24 when the carriage is travelling at a relatively high speed at the time of activation of the shock absorber mechanism, and to provide for relatively fast or unrestricted egress of airfrom the exhaust passage when the carriage is travelling at a relatively low speed at the time of activation. In the illustrated construction, the shock absorber unit 6 includes a U-shaped retainer frame or bracket 25 secured to the frame part 1 by a screw 26 and being formed with inwardly extending tongues 27 for holding in place a block element 28 constituted by resilient deformable material, for example rubber. The block element 28 constitutes a combined striker member and valve part the face of which is aligned with the stem 17 with respect to the direction of carriage travel so as to be engageable with the outer end of the plunger stem element 17 when the carriage reaches a predetermined position in its return travel, the end 29 of the stem 17 providing a valve part cooperable with the block element 23 for controlling the rate of exhausting air from the cylinder chamber through the stem passage 24. The construction and manner of cooperation of the valve part 29 and the valve part 28 vary the resistance to flowing of exhaust air between the two valve parts and hence out of the dash pot cylinder. As shown in Figure 4, the outer end of the stem 17 is rounded convexly, and is formed with a cross-shaped recess 30 which communicates at its center with the exhaust passage 24. When the valve part 29 strikes the valve part 28 while moving at a relatively high speed, the initial yielding of the stem 17 and plunger 14 toward the right as viewed in Figures 1 and 3 is relatively small because of the inertia of the plunger and the stem. Consequently, the left end of the stern formed with the valve part 29 will project into the valve part or block 28 as will be permitted by yielding of the resilient material, the end of the stem 17 moving to the position indicated by the dotted line 31 in Figure 2. In these relative positions of the valve parts 28 and 29, a relatively large part of the open face of the cross shaped recess 30 will be covered by the valve part face 28, so that the air being exhausted must flow over a relatively long lateral path, or rather four relatively long lateral paths to pass out from between the two valve parts. Consequently, the resistance'to exhausting of air from the cylinder chamber will be relatively high and the shock absorbing or snubbing effect relatively great. For accentuating the flow restricting characteristics of the valve means, the four grooves constituting the cross shaped recess may be tapered from maximum width at the center of the recess to minimum width adjacent to the outer wall of the stem 17. With such an arrangement, when the rubber material 28 is pressed against the end surface 29 of the stem 17 with sufficient force to contact all except the extreme outer annular portion of the surface 29, only very restricted openings will be provided for the egress of exhaust air. The constriction of the recess parts is further effected by bulging of the rubber material into portions of the recess in the zone of the surface 29 engaged by the rubber material 28.

When the carriage is travelling at maximum speed at the time of activation of the shock absorber mechanism, the stem 17 may project into the rubber block so far as to deform the latter sufliciently to cause all, or substantially all, of the recess 30 to be closed, thus momentarily preventing exhausting of air, even slowly, from the dash pot cylinder through the passage 24. A slight rebounding of the carriage, insutficient to prevent its subsequently being properly positioned by the locating means (not shown), will then take place, causing enough relative separation of the valve parts 28 and 29 to uncover the recess 30 partially, thereby enabling exhausing of air, at a controlled rate.

When the end 29 of the stem 17 engages the valve part 28 while the carriage is moving at relatively low speed, as for example during a short run, the part 29 does not extend 'so far into the block 28, but extends only to a position such as is indicated by the dotted line 32 in Figure 2. Consequently, the diameter of the area of the valve part 29 engaging, the yieldable material 28 will be less than when the parts engaged each other with 5 the carriage travelling at a high speed, and the exposed or free portions of the recess 30 will be greater and the restriction to egress of exhaust air between the valve parts will be less. Consequently, the air in the cylinder chamber will offer less resistance to the yielding movement of the plunger 14, and the shock absorber mechanism will exert less retarding effect on the carriage.

Irrespective of the speed of the carriage at the time of engagement of the valve part 29 with the valve part 23, the valve parts will cooperate so as initially to provide for relatively restricted exhausting of air, followed by progressively less restricted air exhausting. This is due to the self restoring action of the rubber valve part 28pmgresesively after the initial deceleration of the carriage, causing the recess 30 to be opened progressively. Consequently, the air within the dash pot cylinder will offer progressively lessening resistance to continued travel of the carriage, and the carriage driving means will there fore be enabled to move the carriage completely to its desired limit position.

The construction disclosed embodies the invention in a preferred form, but it is intended that the disclosure be illustrative rather than definitive, the invention being defined in the claims.

We claim:

1. In a typewriter or like machine having a frame member, a carriage member mounted on the frame member for letter spacing travel in one direction and for return travel in the opposite direction, and means for driving the carriage member in one of said directions at different speeds, shock absorber mechanism for retarding the carriage member when it is moving in a predetermined portion of its travel in said one of said directions comprising a first element; means mounting said first element on one of said members; a second element; means mounting said second element on and for yielding movemet relative to the other of said members and for .cooperation with said first element to be moved thereby as said carriage member moves into said predetermined portion of its travel; and means comprising mutually engageable valve parts mounted respectively on said frame member and said carriage member and exercising a control over the yielding movement of said second element relative to said other of said members which varies according to the speed of said carriage member for rendering said mechanism efiective for exerting more or less retarding force on said carriage member according to higher or lower speed of travel of said carriage member as it moves into said predetermined portion of its travel.

2. In a typewriter or like machine having a frame member, a carriage member mounted on the frame member for letter spacing travel in one direction and for return travel in the opposite direction, and means for driving the carriage member in one of said directions at different speeds, shock absorber mechanism for retarding the carriage member when it is moving in a predetermined portion of its travel in said one of said directions comprising a first element; means mounting said first element on one of said members; a second element; means mounting said second element on and for yielding movement relative to the other of said members and for cooperation with said first element to be moved thereby as said carriage member moves into said predetermined portion of its travel; and means for opposing yielding movement of said second element comprising a dash pot including a chamber from which fluid must be exhausted to permit said yielding movement, a passage for exhausting fiuid from said chamber, and a variably closable valve comprising mutually engageable valve parts mounted respectively on said frame member and said carriage member and controlling exhausting of fluid through said passage and being automatically adjustable in response to different speeds of said carriage member as it moves into said predetermined portion of its travel for providing relatively restricted exhaust flow of fluid through said pas- 6 sage when said speed is relatively high and for providing relatively free exhaust fiow of fluid through said passage when said speed is relatively low.

3. In a typewriter or like machine having a frame member, a carriage member mounted on the frame member for letter spacing travel in one direction and for return travel in the opposite direction, and means for driving the carriage member in one of said directions at different speeds, shock absorber mechanism for retarding the carriage member when it is moving in a predetermined portion of its travel in said one of said directions comprising a first element; means mounting said first element on one of said members; a second element; means mounting said second element on and for yielding movement relative to the other of said members and for cooperation with said first element to be moved thereby as said carriage member moves into said predetermined portion of its travel; and means for opposing yielding movement of said second element comprising a dash pot including a chamber from which fluid must be exhausted to permit said yielding movement, a passage for exhausting fiuid from said chamber, and a variably closable valve controlling exhausting of fluid through said passage and including two mutually engageable valve parts which are cooperable in accordance with the speed of carriage member travel for providing between said parts a relatively restricted exhaust opening communicating with said passage when the carriage member speed is relatively high and a relatively unrestricted exhaust opening communicating with said passage when the carriage member speed is relatively low.

4. A construction as set forth in claim 3 in which one of said valve parts is formed on one of said elements and the other of said valve parts is formed on the other of said elements.

5. A construction as set forth in claim 3 in which said valve parts are mounted respectively on said frame member and said carriage member 'and are so positioned on their respective mounting members as to be disengaged from each other when said carriage member is positioned relatively to said frame member other than in said predetermined portion of the travel of said carriage member, and are engaged with each other when said carriage member is in said predetermined portion of its travel.

6. A construction as set forth in claim 5 in which 'one of said valve parts is formed on one of said elements and the other of said valve parts is formed on the other of said elements.

7. A construction as set forth in claim 3 in which one of said valve parts comprises yieldable cushioning mate- 7 rial and the other of said valve parts has a recess to pro:

vide for flow of fluid from said passage between said valve parts when they are in mutual engagement, said yieldable cushioning material being deformable to project into said recess to varying extents in accordance with the rate of relativemovement between said parts at the time of mutual engagement thereof, whereby automatically to provide for relatively restricted exhausting of fluid from said chamber when said carriage member moves into said portion of its travelat relatively high speed and for relatively unrestricted exhausting of fluid from said chamber when said carriage member moves into said. portion of its travel at relatively low speed.

8. A construction as set forth in claim 7 in which the yieldable'cushioning material is rubber, and in which said other of said valve parts has a rounded end contactable with said rubber, said recess being formed in said rounded end. i

9. In a typewriter or like machine having a frame member, a carriage member mounted on the frame member for letter spacing travel in one direction and for return travel in the opposite direction, and means for driving the carriage member in one of-said directions at different speeds, shock absorber mechanism for retarding the carriage member when it is moving in a predetermined portins of it {t a e sai cn s id .tl res iQns comp s a cylin e mounted Q la of sa d mem er r nns r mounted for reciprocation ,in said cylinder; a plunger stem formed with a passage for exhausting fluid from said cy n e ne n m vem n .Q s i p un e fr m a n ma ably restricting theeg hausting of fluid through said pasas in de en nc p th e t v ppr ac n p ed- .of said parts at the time of mutual engagement thereof. 10. A construction as set forth in claim 9 in which ,one of said parts is formed with a recess communicating @Withsaid passage when said parts engage each other and in which oneof said parts isconstituted by yieldable cushioning material deformable to varying extents in depend- ,ence upon the relative approaching speeds of saidparts at the ,time of mutual engagement thereof for varying the ffective size of said recess and thereby variably restrictiugtexhaust flow through said recess .and passage.

7 11. In a typewriter or like machine having a frame member, .a carriage member mounted on the frame member for letter spacing travel in one direction and for .return travel in the opposite direction, and means for driving the carriage member in one of said'directions at different speeds, shock absorber mechanism for retarding the carriage member when it is moving in a predetermined portion of its travel in said one of said directions comprising a cylinder mounted on one of said members; a plunger mounted for reciprocation in said cylinder in the direction of carriage member travel; a stem fast with said plunger and projecting outwardly of said cylinder; a com bined striker member and valve part mounted on the other of said members in alignment with said stem with respect to the direction of carriage member travel and being engageable with the projecting end of said stem only when said carriage member isin said predetermined portion of its travel; a spring for vyieldably urging said plunger toward said combined striker member and valve part; and an exhaust passage extending from within said Icylinder through said stern and opening at the projecting end thereof.

12. In a typewriter or like machine having a frame member, a carriage member mounted on the frame member for letter spacing travel in one direction and for i return travel in the opposite direction, and means for driving the carriage member in one of said directions at vdiiferent speeds, shockabsorber mechanism for retarding the carriage member when it is moving in a predetermined portion of its travel in said one of .said directions comprising a cylinder mounted on one of said members; a plunger mounted for reciprocation insaid cylinder in the :direction of carriage member travel; a stem fast with said plunger and projecting outwardly of said cylinder; :1 combined striker member and valve part of deformable material mounted on the other of said members in alignment with said stem with respect to the direction of carriage member travel and being engageable with the projectingend of said stem only when said ca rriage member is in said predetermined portion of its travel; a spring for yieldably urging said plunger toward said combined striker rnember and valve part; an exhaust passage extending from within said cylinder through said stem and opening at the projecting end thereof; and a recess in said stem projecting end extending from said passage to the outer side surface of said stem.

I 13. In a typewriter or like machine having a frame rnernber, a carriage member mounted on the itame rnember tor letter spacing travel in one direction and for retqti trave in the ran t di ec ion ea -niean a -st -,8 teeth? e rr n s ntqmbs i n p t aid t qns at dift r a sneak stuck .ahse ta me han m for r ard n thewzria e nb w ea t i tmy ns a predetermined portion of ;its' travel in said one of said directions comet sias a sr i qe mou ned 9 2 .1 of s i m mbers; a Plun e omitted for r c r c t on s i i yltnder in th directisn .q sa ria e memb tare a Stem s w sai P ane an Protes ing wa d n sai yl n e va ombined striker rnernber and yalve part of rubber mounted -.Q F-Q .l of sa d .ms nhfls in a men i said e with respect to the directionof carriage member travel a d eia sn sahl w h th ie t n cs o d stem only when said carriage member is in said predetermined r t 9 f i ave a s i to y el ly urging s plunger toward said combined striker memberand valve part; exhaust passage extending from Within said cylinder h t b-r ei fi em aa QPQ l Q at the p oj t d thereof, said projecting end being gonvex; and a crosssh r 9% in said FQ stem a mm i a with said passage and extending to the outer side surface stem- 14. In a typewriter or like machine having a frame mem e a Ferns m mbe mqunt nn t ram m mher for letter spacing travel in one direction and for return travel in the opposite direction, and means for driving .the carriage member in one of said directions, shock absorber mechanism for retarding the carriage member Whe n itis moving in a predetermined portion of its travel a in said one oflsalid directions comprising a first element;

means mounting said tirst element on one of said members} asecjond element; means mounting said second elejment ort and for yielding movement relativeto the other of'saidmembers and for cooperation with said first element to be moved thereby as said carriage member moves into predetermined portion of its travel; and means for opposing yielding movement of said second element comprisinga ,pot including a chamber from which fluid must .be eiihausted to permit said yielding movement, :a passage for exhausting fluid from said chamber, and .a va riably closable .valve controlling exhausting of lipid through said passage. said valve having two mutually engageable parts variably cooperable with each other according to the force one exerts upon the other for initially providing for relatively restricted fluid exhaust at the moment of activation of the shock absorber mechanism, and for-providing for progressively less restricted exhaust as the race exerted by said one of said parts on the other ,dimishes in consequence of retarding of the carriage.

15. In a typewriter .or like machine having a frame member, a carriage memberinounted on the frame member for letter spacing .travelin one direction and for return travel in the opposite direction, and means for driving the carriagemember in one of said directions, shock absorber mechanism for retarding the carriage member When it is moving ina predetermined portion of its travel in said one of i said directions comprising a cylinder mounted on,o,ne o.f said members; a plunger mounted for reciprocation in said cylinder; a i plunger stem formed with a passage for exhausting fluid from said cylinder upon movementvofsaid plunger from .a normal position in "said cylinder, said plunger stem having an end project- .ing beyond said cylinder and formed with a transverse recess communicating with said passage; and a part formed of deformable material mounted on the other of saidfmembers and being engageable with the recessed end of said stem when said carriage member ,moves into said predetermined portion of its travel for variably partially closing said recess according to the force with which said partengages saidplunger stem end.

.16. In typewriter or like machine having a frame member, acarri-age member mounted for movement relative to said frame member, and means for moving said carriage member relatively to said frame member: shock bsorb? n w t exe tin e r n fo id {Carra .1 11 .t satt a a ammonit s Hait a 9 it movement relative to said frame member, said shock absorber means comprising a fluid cushioning unit mounted on one of said members and including a cylinder and a plunger mounted for relative reciprocating movement, and first valve means for permitting egress of fluid from said cylinder upon movement of said plunger in one direction relative to said cylinder; and a striker unit having a second valve means mounted on the other of said members in a position to be engaged by said first valve means for causing movement of said plunger in said one direction upon mutual engagement of said first and second valve means, said first and second valve means being cooperable for controlling the rate of egress of fluid from said cylinder according to the rate of relative movement of said carriage member and said frame member as said carriage member is moving in said predetermined portion of its movement relative to said frame member.

17. In a typewriter or like machine having a frame member, a carriage member mounted for movement relative to said frame member, and means for moving said carriage member relatively to said frame member: shock absorber means for exerting retarding force on said carrialge member throughout a predetermined portion of its movement relative to said frame member, said shock absorber means comprising a fluid cushioning unit mounted on one of said members and including a cylinder and a plunger mounted for relative reciprocating movement, and first valve means for permitting egress of fluid from said cylinder upon movement of said plunger in one direction relative to said cylinder; and a striker unit having a second valve means mounted on the other of said members in a position to be engaged by said first valve means for causing movement of said plunger in said one direction upon mutual engagement of said first and second valve means, said first and second valve means being cooperable for controlling the rate of egress of fluid from said cylinder inversely to the rate of relative movement of said carriage member and said frame member as said carriage member is moving in said predetermined portion of its movement relative to said frame member.

18. In a typewriter or like machine having a frame member, a carriage member mounted for movement relative to said frame member, and means for moving said carriage member relatively to said frame member: shock absorber means for exerting retarding force on said carriage member throughout a predetermined portion of its movement relative to said frame member, said shock absorber means comprising a fluid cushioning unit mounted on one of said members and including a cylinder, a plunger mounted for reciprocating movement in said cylinder, and a stem element projecting from said plunger,

said stem element having fluid passage means communicating with the interior of said cylinder for permitting egress of fluid from said cylinder through said stem element when said plunger is moved in one direction relatively to said cylinder; and a striker unit mounted on the other of said members in a position to be engaged by said stem ele. ment to cause said plunger to move in said one direction and to substantially cover said fluid passage means in said stem element so as to restrict the egress of fluid from said cylinder as said carriage member is moving in said predetermined portion of its movement relative to said frame member.

19. In a typewriter or like machine having a frame member, a carriage member mounted for movement relative to said frame member, and means for moving said carriage member relatively to said frame member: shock absorber means for exerting retarding force on said carriage member throughout a predetermined portion of its movement relative to said frame member, said shock absorber means comprising a fluid cushioning unit mounted on one of said members and including a cylinder, at plunger mounted for reciprocating movement in said cylinder, a stem element projecting from said plunger, said stem element having fluid passage means communicating with the interior of said cylinder for permitting egress of fluid from said cylinder through said stem element when said plunger is moved in one direction relatively to said cylinder; and a striker unit mounted on the other of said members in a position to be engaged by said stem element to cause said plunger to move in said one direction and to substantially cover said fluid passage means in said stem element so as to restrict the egress of fluid from said cylinder as said carriage member is moving in said predetermined portion of its movement relative to said frame member, said striker unit having a part formed of yieldable materal into which the end of said stem element which strikes said striker unit may project, said end of said stem element being convex and having fluid passageways communicating with said fluid passage means and tapering in a direction away from said fluid passage means so that the deeper the projection of said stem element into said yieldable material the greater the coverage of said fluid passage means and said fluid passageways and the more the restriction of the egress of fluid from said cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 

